1. Field of the Invention
This invention relates to a novel process for preparing organo N-hydroxyimidates. More particularly, this invention is directed to a process for preparing organo N-hydroxyimidates by reacting an organonitrile with an organic alcohol and with a hydrogen halide selected from the group consisting of HCl, HBr and HI, in the presence of an organic solvent, under anhydrous conditions, to form the corresponding organoimidate hydrohalide, and then reacting the resulting organoimidate hydrohalide with a hydroxylamine salt and ammonia gas in the presence of an organic solvent, under anhydrous conditions, to produce the corresponding organo N-hydroxyimidate.
2. Prior Art
Organo N-hydroxyimidates are a known class of compounds and have long been recognized as valuable intermediates in the synthesis of substituted hydroxylamines. Recently, organo N-hydroxyimidates have become valuable intermediates in the production of agricultural and pharmaceutical products.
Classical methods for preparing organo N-hydroxyimidates involve reacting organoimidates with hydroxylamine, the organoimidates being produced from the reaction of organonitriles and alcohols. This approach, however, as reported in U.S. Pat. No. 4,339,444, results in poor yields. Furthermore, this method requires the inconvenient and cumbersome step of handling moisture-sensitive intermediates (e.g., Organic Synthesis, Collective, Vol. I, Page 5). Other reported methods involve reaction of corresponding iminoester hydrochloride compounds and hydroxylamine hydrochloride. For example, J. Houben and E. Schmidt, Chem. Ber. 46, 3616 (1913), Y. Tamura et al., J. Org. Chem. 38, 6 1239 (1973) describe the preparation of ethyl N-hydroxyacetimidate by reacting acetiminoethylester hydrochloride and hydroxylamine hydrochloride. The reported yield was 66.3%.
A. Werner and H. Buss, Chem. Ber. 27, 2193 (1894) have reported an attempted reaction of alpha-chlorobenzaldehyde oxime with sodium ethoxide, in which ethyl N-hydroxy benzimidate was identified along with diphenyl urea as reaction products.
Co-pending, commonly assigned application Ser. No. 599,433 of C. T. Mathew et al., filed Apr. 12, 1984, discloses a process for preparing organo N-hydroxyimidates by halogenating the corresponding oxime compound in an organic solvent which does not react with the halogenation agent under the reaction conditions and reacting the resulting 1-halo-substituted oxime compound with the alkali metal or alkaline earth metal salt of an alcohol.